Method and apparatus for automatically regulating the grate speed in furnaces with traveling or chain grates



Jan. 6. 1925.,

R. BOSSELMANN METHOD AND APPARATUS FOR AUTOMATICALLY REGULATING THE GRATE SPEED.

IN FURNACES WITH TRAVELING OR CHAIN GRATES Filed June 27, 1921 2 Sheets-Sheet 1 Ian. 6. 1925. 1,521,669

R. BOSSELMANN 4 METHOD AND APPARATUS FOR AUTOMATICALLY REGULATING THE GRATE SPEED IN FURNACES WITH TRAVELING 0R CHAIN GRATES Filed June 27,1921 2 Sheets-Sheet 2 Patentedxl. 1925.

Brennan nossnnmzann, ,or BERLIN, ennmamr.

. THO!) AND APPTUS FOR A UTOHATIGALLY REGULATING THE GEATE S m FURNACR 1 Application filed June 27,

To all whom it may concern:

Be it known that I, RIOHARD BOSSEL- MANN, engineer, residing at Berlin,N.W. 52 Spenerstrasse 33, German have invented certain new and useful mprovements in Methods and Ap aratus for Automatically Regulating the rate- Speed in Furnaces with Traveling or Chain Grates, of a hich the following is a specification.

In mechanical stoking plants,vfor example, chain and traveling grate furnaces, the stoker has to give special attention to the regulation of the grate-speed or rate of sup ply of fuel corresponding: to the combustion 1 required at the time. f the speed is too great unburnt fuel falls over the end of the grate intothe clinker-chamber; if the speed is too small, superfluous air passes through the more or less considerably cooled and contracted layer of clinker already in front of the'grate-end. In both cases the eflicienc of the furnaces is obviously reduced. Now the object of my invention is t9 render regulation of the grate-speed independent of the stowers attention whenthe load,

1 for example of a steam boiler, is a varying one, and to-efiect this regulation automati cally. To this end my invention provides a method already proved to be successful and also apparatus suitable for carrying out the" method.

'According to my. invention the tempera-r ture of the coolmg water which flows. through the bridge or dam at the rear end-of the grate is utilized to influencev variations in the speedat which the grate. is drlven, saidcooling water being conducted through an extensible or expansible member, which. on its own part efiects the regulation of the grate-drive. l

Two embodiments ofmy' invention are shown by way of example in the accompanying drawing whichlshows in Figures 1 and 2 diagrammatically thoseflembodiments 1n 4 combination it-h a'travling grate driven lien drive.

a direct current motor .or bymeans' ofva di 'awing,,- 1 indicates in .:-I VELI'NG OR CHAIN GRATES.

1921. Serial at; 480,851.

'valve 13 influenced by a float 12 and pro- 8 vlded with an outlet 14 serves to supply water always at a uniform rate, the float 12 keeping the water-level in the tank 11- constant, it follows that a constant flow of water issues from the nozzle 14 into the funnel 15 and therefore through the pipe 9- into the bridge 8.

The cooling water discharge piping 10 terminates in a coil 16 mounted in a vessel z, 17 which .is filled conveniently with colzaoil. On this vessel is-Inounted an expansion device 18 which'is connected with theinterior of the vessel,..and carries a cup 19 of vmercury. In this way more or less ofthe contacts 20 dip into the mercury in accord- Y ance with the height of the cup 19, and'consequently more or less of the resistance 21 becomes sh'ort-circuited. The resistance21 is connected in-the shunt or excitation circuit of the shunt motor 4. Whentherefore the temperature rises, that is, when the grate is moving too quickly the speed of the, motor must be reduced, wareas when the temperature falls or the grate runs too slowly, said 5 ed would be increased. l "The above-escribedapparatus operates: in the following manner. '7 i v The flow of cooling'water from the nozzle 7 14 ,is so chosen that when there is normal combustion of the fuel, the cooling water fflowing from the bridge 8 into the pipelo I and worm 16, has a certain temperature,'-.

18 will then have raised the mercury-cup to such a level that about half-the resistance 05; i 21 is short-ci'rcuited, and with the corre-.

spending field-strength the motor 4 will run at a moderate speed corresponding to that suitable for normal combustion. When some of the load is taken off the boiler, the stoker reduces the draught-L The consequence is that the fuel burns more slowly and in its still burning condition gradually flows over the bridge 8. The temperature of the bridge and of the cooling water therefore rises. The contents of the vessel 17 become warmer and by means of the expansion device 18 give an upward movement to the mercury-cup 19. In this Way a further portion of the resistance 21 is short-circuited and the motor-speed reduced. The heating action and fall in motor-speed continue until the latterhas become suitable for thev combustion on the grate.

If the boiler becomes more heavily loaded, the draught is increased, the coal burns away too quickly and the bridge 8 becomes abnormally cooled, whereu on the reverse of the above-described regu ating movement takes place.

By means of the above-described apparatus, it is easy to adaptthe grate-speed to the strength of the draught at any time, so that the stoker does not need to trouble himself about the gratespeed at all. He has onlythe dampers to look after and can in theabove manner obtain the 'neces-' sary activity of combustion without wasting coal.

Instead of using an electric motor for driving the worm 5 advancing the grate, it may be employed, as shown by Figure, 2, a belt drive comprising the conical pulleys 22 and 23 and the belt 21. The belt 21 can be displaced on the pulleys 22, 23 by means of a rod 20 so as to vary the speed of the worm 5 and the grate 1. The rod 20 is connected to an angle lever 19 which is controlled by the movements of the expan sion device 18. The other parts of Figure 2 are the same as in Figure 1-. Also the working of the arrangement according to Figure 2 is analogous to that, of the driving system shown in Figure 1. According to the degree of expansion or contraction of the device 18 dependent on the temperature of the coolin water traversing the bridge 8 there is a isplacement of the lever 20 and of the belt 21 in the sense of the arrow 24 or in the opposite direction respectively, whereby the speed of the grate 1 is automatically regulated in the desired manner.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed I declare that what I claim is 1. Means for automatically regulating the movement of a traveling grate for furnaces upon. which the fuel is fed from a receptacle, id means comprising'a hollow bridge maintained adjacent to the discharge end of the traveling grate, means for supplying fluid under pressure to the interior ofthe bridge, means for conveying heated fluid from the bridge to acontainer, an expansion element associated with the container, and means for controlling the rate of travel of the grate relative to the temperature of the fluid which is conveyed from the bridge.

2. In a device of the character set forth, the-combination of a movable grate, a hollow bridge maintained to lie across the tion of the bridge being such as to be surrounded by fuel, means connected with the bridge for supplying fluid under pressure thereto, and means for conveying fluid from the bridge to a chamber, an expansible element attached to said chamber actuated by the means contained within the chamber, the temperature thereof being controlled by heat conveyed thereto from the means for conveying fluid from the hollow bridge, and means operatively associated with the .expansible element for controlling the drive of the traveling grate.

4. In a furnace structure, the combination with a traveling grate, mechanical means for feeding fuel thereto, and a speed changing device operatively connected with the grate, comprising a hollow bridge which traverses the grate adjacent to its dischar e end, means for supplying fluid to the bridge and from the bridge to the controlling means of the speed changing device, such means being constructed and o-rganized so that a change of temperature of the fluid discharged from the bridge will control the movement of the speed changing device and the rate of travel of the grate.

5. In a furnace structure, the combination with an endless traveling grate, means for feeding fuel thereto and means for controlling the rate of travel of the grate, of a hollow bridge maintained to traverse the grate and maintained above the surface thereof, means for supplying fluid under pressure to the bridge, a discharge pipe ha ing an intermediate coil, a receptacle for expansible fluid within which is located the coil, an expansion chamber operatively Nil connected withmeans for controlling the plied from the bridge to determine the rate rate of travel of the grate to accord with of travel of the grate.

the movement of the expansion chamber. In testimony whereof I afiix my signa- 6. In a device of the character set forth, ture in presence of two Witnesses.

the combination with a traveling grate, of RICHARD BOSSELMANN. a hollow bridge maintained to traverse the I grate, said bridge having an inclined for- Witnesses:

ward end, means associated with and con- 7 WILLY WIL E, trolled by the temperature of the fluid sup- 7 HELENE VON Mina. 

